A VERY popular Ghanaian (Pidgin English) expression used in multiple senses (depending on rising/falling intonation):

1. in the same sense as the words "Dude" or "Homie." Synonymous with the American "Jack" or "Joe" as a way of addressing another person directly. Supposedly believed to have originated from the Chicago-based slang "Charlie" (pron. "Chali"), used in the same vein to address someone directly.

2. used with "Oh" as an expression of disappointment, pity, sympathy.

3. used with "Oh" as an expression of agreement with someone else's statement. Used in the same vein as "I know right?" or "Tell me about it."